They called him a better quarterback than Peyton Manning, who kicks off the NFL season tonight against the Super Bowl Champion Ravens. Then they called him the NFL's greatest bust. Now they call him Montana State Prison Inmate No. 3005025. Facing one final shot at salvation, Ryan Leaf tells the true story of his downfall to the most unlikely of writers—his cell mate.

Fuckin’ hell! You and me aren’t gonna have to fight, are we?”

Those were the first words I spoke to Ryan Leaf, who all but blotted out the lights when he entered my 12-by-16-foot cell behind the Sheriff’s Department in Lewistown, Montana last October. The man is six-foot-five and 242 pounds, with a set of shoulders like a range of the Rockies. At 52, I wasn’t at all sure I had enough knockin’ out left in me for all he’d take.

“Nah,” he said with a shrug and the slightest of sheepish grins. Then he went to sleep for two days.

I’d heard about a celebrity inmate on temporary time-out from addiction treatment making his way around the rotisserie. His name, I admit, meant nothing to me. I’m an import from England; we don’t swaddle ourselves in body armor prior to playing a game. American football, to me, is overly refereed rugby for the squeamish. Even real football, what you Colonials insist on calling soccer, means little to me any longer. I’ve grown too old and brittle for hooliganism, so there hardly seems any point. I am simply not a sports fan.

This was to serve me well with Leaf. After a couple of days he crawled out of both his doldrums and his tiny, one-size-doesn’t-fit-all bed at about the same time. We began some stimulating conversations, on any topic other than football.

That lasted two more days, until Montana’s temperature plunged toward 20 below and we were joined by a homeless man who had stolen a car in order to drive drunk just so he could get in the jail and out of the cold. Recognizing Leaf but not any degree of the courtesy that must mark such close quarters, all he wanted to do was talk about football. The former Number 16 did not. One interlude I missed, related by Leaf: “He sat at the table, just listened to me all the way through a long and fairly intimate conversation with my mother. Then immediately all he wanted to do was go on about a fuckin’ Bucs game. Hadn’t I made it clear I didn’t want to talk about football?”

Everyone wants to talk to Ryan Leaf about football. People talk about how he led his high school to the Montana state championship in 1992. They talk about his days at Washington State University, where he threw for 33 touchdowns in a single season, setting a Pac 10 conference record and leading the Cougars to their first-ever Pac 10 championship win and a trip to the 1998 Rose Bowl. Or they talk about how, in 1997, he put up the second-highest passer rating in the States, came in third in Heisman Trophy voting, won Pac 10 offensive player of the year and was chosen as part of Sporting News’s first-team All-Americans. But mostly they talk about the San Diego Chargers taking Leaf as the number two pick in the 1998 NFL draft, with debate raging that he should have been in pole position. But Peyton Manning, perceived as more mature, won out. It would prove prophetic.

Leaf’s four-year contract with the Chargers totaled $31.25 million. His $11.25 million signing bonus was the highest in sports history for a rookie. During his four-year professional career Leaf played—poorly, if at all—for the Chargers, Dallas Cowboys, Tampa Bay Buccaneers and Seattle Seahawks.

By 2002 his football career was over, and the talk changed. “I’m considered the biggest bust ever in the NFL,” he tells me. He’s right. That’s a direct quote from MSNBC. And ESPN. In fact, “the next Ryan Leaf” is sports-speak for each year’s most spectacular draft flameout. ESPN’s “25 Biggest Sports Flops of 1979–2004” ranked him in the top slot. In 2010 the NFL Network agreed, naming Leaf the number one NFL quarterback bust of all time. Leaf even picked up the tag. In his 2011 autobiography, 596 Switch (which covers only his college days), he describes himself as “Ryan Leaf, the NFL bust…the PR train wreck…the cocky jerk.”

These days everyone wants to talk to Leaf about his decade-long struggle with painkillers, his rehab attempts and his incarcerations. Most major media outlets, including the sweaty wretches manning sports desks across the country, have approached him. Countless letters arrive asking for interviews. Leaf declines them all. This article contains the only for-publication interviews he has consented to since his incarceration, indeed, since his, as he refers to it, “spectacular return to drug addiction.” They were conducted start to finish inside a jail cell and document the conversations of two men wearing convict orange, both wondering what the hell happened to their lives, his story a little more complicated—and public—than mine.

Here is how a man once perceived as America’s next great quarterback wound up in a cell with yours truly. It was October 2012 and I was in there accused of committing a crime that never occurred; I was released in early December. Leaf’s latest sentence—seven years (with two years possibly knocked off for good behavior) for burglary and criminal possession of dangerous drugs—started with nine months at Nexus, a behavioral-modification facility in Lewistown. The privately owned lockdown rehab is run for Montana’s Department of Corrections. Its dynamic is that of a community overseen by inmates thrown together and forced to interact as family members with only minimal guidance from staff. The governing principle acknowledges that addicts are extremely sneaky fuckers. It assumes they’ll fool any outsider, no matter how well educated and well intentioned, but won’t waylay 80 other hypes, junkies and meth heads. Fooling the educated and naive is one thing. Deceiving other addicts is quite another.

Leaf didn’t see it working. The problem, as he saw it, was Ryan Leaf. “I’m a leader. I saw what was happening. During my first six weeks, when I was trying hard, I was leading people in a productive way. During the next six weeks I was bumping heads. I saw other people start to act up as well.”

He experienced an aloof, isolationist epiphany around week 12. “I went to the office and told them I’d had enough of the unspoken competition. Told ’em I wanted to get the most out of the program, was prepared to give up any trace of individuality to see if it would really work for me.”

Leaf’s problems started with an addiction counselor we’ll call Yosemite Sam. Leaf mocked Yosemite Sam, and his new self-proclaimed mentor wrote him up. The system cracked down. “They need to retain a little perspective on what they’re trying to do there, trying to accomplish,” Leaf explains.

His first mistake was walking around inside the facility without an escort. Number two was refusing to read in a group. The next hiccup occurred when Yosemite Sam checked Leaf’s room for compliance; the former quarterback couldn’t resist saying, mockingly, “Tighten up my bed corners for me, will you?” Thin-skinned counselor scurries off to office: write-up number three. When Leaf was asked to expound on his failings in therapeutic community (oh, it hurts to report such touchy-feely feculence), he delivered his explanation with a sneer: “I was a smartass. I said I’d interfered with the peace and harmony of another family member.”

Written up again. Off to jail to internalize the errors of his ways.

At his hearing, administrators accused Leaf of being unwilling to change. He disagrees. “I just don’t see it’s going to work. I’m being honest. I don’t see nine months of this is going to give me the equipment. I don’t see the sustainability. I totally tried to join in, but it felt phony, like I was lying. I knew if anyone put pills in my hand, I was gonna take ’em. Their doctrine is that it’s not what you’ve done, it’s what you’re doing that counts. But I have a terrible time disregarding what I’ve done.”

Leaf brought problems with discipline and attitude to San Diego in 1998. The rookie quarterback didn’t settle in well with his teammates. He yelled at hecklers and got into screaming matches with coaches. In the most famous incident, caught on video, Leaf exploded at a San Diego Union-Tribune reporter in the Chargers’ locker room, screaming, “Don’t talk to me, all right? Knock it off!” until teammates hauled him away.

His atrocious attitude was matched by a woeful work ethic. Then physical problems affected his performance. He was fined and suspended. His record, losing 11 of his first 17 starts, was the final straw. The Chargers released him in March 2001. He signed with the Bucs and was let go without making a single appearance; the Cowboys then released him after only four appearances, all losses. Once labeled the world’s next great quarterback, he retired—blaming injuries—before ever playing a game for the Seahawks. In 1998 he had envisioned a 15-year career. He would have been winding down his life’s work as a pro football player today, at the age of 37. Instead, he was out on the street at 26.

“I’d pretty much achieved the pinnacle of what success was available to me. I wanted to keep climbing, but all I could do was plateau. That held no interest. I guess I just got involved in sliding down the other side, as far and as fast as I could,” he says. With a plate-size right hand he gestures downward, a swift, chopping motion. “There I was, a 21-year-old millionaire. I’d reached the peak of every ambition I had as a child. Fifteen years later my perspective’s very different, but essentially the problem’s the same.”

Football’s quintessential Americanness ramped up Leaf’s self-recrimination. He interpreted his behavior as a desecration of the whole country. By squandering his on-field talent, Leaf felt he’d attacked an entire ethos and tarnished the institution of football. “I was drafted with Peyton Manning, and that certainly didn’t help,” Leaf says. “He’s arguably the best quarterback of all time, so we were looked at under the same microscope. And he handled everything just like he was supposed to.”

Leaf is congenitally unable to share the spotlight, even in a grubby little jail cell or a state-sponsored lockdown rehab facility. If he couldn’t be the best at being good, it must have been cheap work for his subconscious to suggest he become the best at being bad. Painkillers helped. “It was the expectations everybody had,” he says, explaining what led him to pills. “It wasn’t at all related to the way the drug made me feel, not at the beginning, not ever. It was what I didn’t feel—all that disappointment. I was lonely and sick of being criticized. But the bottom line is, I wanted to get high.”

Get high he did, shoveling down every opioid painkiller he could purchase. Oxycodone. Hydrocodone. The pills felt great when he was in physical pain, then they felt great when he was depressed about it, and then he was a drug addict wondering how the fuck that happened. “It’s not the pain. You can pull a bone out of my body and I’ll stay on that field until the game is won,” he explains. Taking pills “initially started out as pain treatment, but after a very short while it became something else. When I was taking the pills, I didn’t have to deal with my feelings of being a failure.”

When he couldn’t buy, he begged. In 2006 he began coaching quarterbacks at West Texas A&M, a gig that lasted two years, until he was caught hitting up players for pain pills. When he couldn’t beg, he burgled. In 2009 he caught burglary and drugs charges in the Great Republic of Texas for breaking into a player’s house, receiving 10 years’ probation.

Extraordinarily, it was Leaf’s remoteness from criminal culture that led to this downfall. The lifelong jock simply lacked street cred. “If I could’ve found a drug dealer, I would’ve never gotten in trouble. If I’d made the right connections, I could’ve said, ‘Here’s a hundred grand. Give me several years’ supply.’ Then I’d just go sit in my cabin.”

For a while Leaf latched on to an internet source that sold pills through the mail from Florida, a state on the cusp of pain-management-clinic corruption. He forked over $19 per 10-milligram Percocet pill, or $570 for a tub of 30, from the Sunshine State. I’m currently not short of drug dealers to consult concerning comparative cost structures. At that time, the same pills were peddled at 10 bucks a button on the mean streets of Great Falls, Montana. In a bulk buy they’d probably go for $7 each, about one third of what Leaf was paying.

The setup was ideal until Leaf’s attitude sabotaged him; he refused to give his e-dealer a credit card number. “I was just too mean, man. My mail carrier told me he normally saw only a dozen COD packages a year, yet he’d had eight for me in half that many weeks.” In March 2012 law enforcement launched an investigation. When police searched Leaf’s house they found a pill bottle stashed in a golf bag and traced it to an acquaintance, who claimed Leaf had stolen it. Leaf was charged with burglary and theft.

Bailed for $76,000, he was busted again three days later for entering an unoccupied and unlocked house outside Great Falls and cleaning out the bathroom of three bottles of prescription painkillers. The owners came home as he was leaving. He talked his way out with the old “Sorry, wrong house” routine and did a downfield dash. The owners called the police. When they described their uninvited guest—a “tall man with an athletic build”—the cops suggested they check their medicine cabinet to see if anything was missing. Bingo. The GPS in Leaf’s truck verified it had been there at the time of the robbery and had stopped at five to 10 other houses in the area. Montana police hauled him in. “I turned up looking like a bum, man. I had long hair, for me, and a full beard that grew right down my neck.”

He served 10 weeks in Montana’s Cascade County Detention Center while his warrants were worked out, including two from Amarillo, Texas for breach of parole. After being convicted, he readily accepted the DA’s first plea bargain of seven years, two suspended. Leaf feels his sentence was too light.

“If they put me in Montana State Prison for five years, that’d be okay by me. I don’t really have any drive to be out. I’m just so miserable out there.”

One day Leaf received a postcard from a cousin then in Spain, a whole lifetime still before him. I heard a little-boy warble in Leaf’s voice as he read me the message. Years earlier, Leaf and a cousin had taken a six-month grand tour of Europe after his football career had ended. “It was just like everyone else does after college,” he incorrectly assumes. “Except it was all Ritz-Carltons for us, not hostels, and we rented cars and took sleeper trains instead of hitchhiking. All that time in Europe, I was recognized only twice. Both times it was Americans.” Later, from a Montana jail, he placed a collect call to his mother and stood holding the postcard at arm’s length as he talked, describing it to her.

Leaf, the oldest of three boys, was raised in Great Falls by his father, an insurance salesman, and his mother, a registered nurse. At a sentencing last year, Leaf told the court, “They believe I’ve held them for ransom for 36 years, and I don’t understand why I should have to do that anymore. I’m lazy and dishonest and selfish. These were behaviors I had before my addiction kicked in. Five to 10 years of Ryan-free drama for my family, this community—particularly for this nation—would be pure bliss.”

A prison cell hasn’t softened the feeling. “My worst humiliation was putting my family through hell,” he says with a sigh, before explaining how the pills fit nicely with his other addiction: isolation. “I just sat in my lake house all alone. I’d be there for weeks, and I loved it. But it was so unhealthy. I got high and watched TV and slept. I just liked it. I didn’t feel anything. I just lay around, loving it. Anyone who tried to stop me, I was just, ‘Fuck you, let me go feel good.’”

I admit it all sounds serene. “I just wasn’t with others. No one ever saw me use,” he says. “No one knew. I ignored my parents, my brothers, never had relationships with women. Being around people, they wanted to talk about football. That was always my identity.”

A millionaire ex–football player, even—or especially—one addicted to pills, is someone to use. “I never can really figure out other people’s motives, so I have a hard time trusting anyone. Women love to be treated to things they can’t afford themselves. With men it’s more occupational.” Sports-oriented, making introductions? “Nah, my first job outside football was in financial services, working with my ex-father-in-law. I thought he was going to teach me all about wealth management, the intricacies of how to help people. Turned out his only interest was that I knew a lot of people with a lot of money.”

Better then to stiff-arm all newcomers and not run any risks. He tries to avoid those who are attracted to his extraordinary success; by Leaf’s logic, it means they are dumb by definition—they don’t see him as a failure.

“The people who haven’t let me down through all of this are those I took for granted before,” Leaf says. “My defense mechanism is to rationalize that it doesn’t matter enough to really experience other people, because I’ll never see him or her again.”

But people want to believe in heroes, and the reception to Leaf’s 2008 stint in rehab (when it still appeared successful) was uniformly positive. People who’d never met him were proud, praising his having accomplished something they understood to be desperately difficult.

Now Leaf feels like a hypocrite. “After the rehab in 2008, I was right back in the public eye. I wrote my book 596 Switch; then I had to go out and speak about it.” The book covers only his career at Washington State, but that didn’t stop people from asking about his addiction. “At the signings and the speaking engagements, people wanted to hear me talk a lot about overcoming my addiction. It was humbling to speak so publicly about things that were bothering me privately.” What things? “Becoming a drug addict, not succeeding at what I wanted to succeed at.”

One particular appearance sticks in his mind. In 2011 the University of Oklahoma was the top-ranked football team in the country and had recently lost its 22-year-old starting linebacker to a painkiller overdose.

“It felt like such an honor, and I put in a lot of effort to give an awesome presentation. Three and a half months later I did exactly the opposite.”

This is how Leaf’s latest relapse happened: During treatment for a benign brainstem tumor in 2011, Leaf started to use again, in the most authorized and understandable of ways. “The pills were in front of me because of medical issues. I’ve come to believe that I cannot take painkillers ever again in my life.”

Leaf underwent a craniotomy with local anesthetic only. Actual pain management, Leaf says, is “just an excuse, like it was my reward for all I’d been through. It was what I remembered, that euphoria and lack of any physical or emotional pain. I was hooked immediately after taking the first pill.” He had sacked himself again. “I fooled myself into believing I could control it, as all addicts do. I thought I wouldn’t get caught and I would continue on with my life after my treatment was over.”

But no, the world changes, the tensions bleed away. No more failure. No more hypocrisy. No more expectations. There it is, the drifting delight of smoothed-out edges. Too much to resist. Fuck you, let me go feel good.

“I rented a house in Venice Beach, and my treatment was in Santa Monica. I started to use again on the first of December. It was so easy. I didn’t have to think about anything. I’d go to treatment, get a pill and then go to a movie theater where I’d be all alone through the day.” Leaf sat, aimless and uninvolved, observing show after show, a shadow creature adrift in unreality. “I’d stay there till they shut.” Day after day alone in a dark movie theater. “I went through the whole radiation therapy that way. After eight weeks, I was fully addicted again. I absolutely believed I’d quit as soon as I got back to Montana.”

I believe he believed it. Brain tumors scare the hell out of everyone. Trepidation is a desperately horrible feeling, one he could switch off with ease. I personally detest that unshakable sensation of something bad about to happen; lately I’m an expert. It seemed stupid to Leaf not to alleviate it. But life ain’t over. Bad times will roll around again as sure as Elvis is eternal. What happens next time? “The biggest message I learned is that I needed to ask for help,” Leaf says. “But I didn’t. Even though I knew I needed to, right while I was living it, I couldn’t ask for help. I still can’t.”

Then jail ain’t seen the last of you, mate.

I sort of miss seeing Leaf galumphing around our shared quarters in XXXXL convict-orange pajamas or wedged onto a sub-six-foot, bolted-to-the-wall bunk, head rough against the end wall, huge feet dangling over the end. Spend an extended period in close quarters with Leaf and it’s obvious he tends much more toward attention-seeking rather than outright raffish behavior. Silences are often broken by complaints about food, the absence of exercise, the 24-hour-a-day confinement and the lack of a TV. Other moments are filled with shameful “singing.” His horrible howl-alongs made almost anything from the 1980s even worse.

Sometimes he spoke with disinterest about the Bentley Azure he owns in California (though when we played Monopoly, he insisted on being the car). He talked about his custom-built home in Denver, his lakeside retreat in Montana and his crash pad in San Diego, which looks out onto the Bentley. Or the time he mentioned having funded four Thoroughbreds. Once, when Sara Bareilles’s “Love Song” came on the radio, he commented casually that she was his brother’s ex. Then there was the story about Shania Twain, who insisted on wearing his jersey for a photo.

Leaf certainly isn’t shy about soft-soaping his celebrity, especially to alleviate the inconveniences of incarceration. The judge at his sentencing reduced a plea-bargained punishment Leaf had already signed, an unheard-of event. A similar thing happened when Leaf joined me in October. A few hours after Leaf was removed from rehab and handed a 10-day sanction for misbehavior, his sentence was abated to eight days, no explanation. Leaf just shrugged. On his second night, an officer brought him an additional mattress pad after lockdown. Shrug again.

We’ve stayed in contact by mail. In the way of snakes eating their own tails, Leaf returned to rehab at Nexus for seven weeks, until he landed back in the same cell where we’d met. How did that happen?

“I was asked—or should I say told—to sign a contract. Among many things it stated I could ‘wear only Nexus-issued clothing’ and I was to ‘resign or quit any and all committees and would not volunteer, facilitate or co-facilitate any committees.’ On December 28 I did some service work by setting up chairs in the gym [and then] helped Phase One [new inductees] with their criminal cycles by using mine as a teaching tool. [That] night I went outside to recreation and it was near zero degrees, and I wore my own sweatpants.”

The next day a shift supervisor accused him of violating his contract. Then a roommate tattled to security that Leaf said he wanted to drag Yosemite Sam around by his hair, something he calls “an absolute lie.” Fiction or fact, talking about it—instead of doing something about it—was right. “Recognizing your thinking errors and choosing intervention thoughts or other thoughts so you don’t act on it is what I did, so the tools were working,” Leaf writes. “Just like it will have to work when I want to take a pill or walk into a home and steal a pill. It was working, slowly but surely, but for Yosemite Sam it wasn’t fast enough. This is just not a quick escape route back to the world to do it all over again. This has to work. This is my last chance. Whether it takes nine months or five years, it has to work.”

The relationship with Yosemite Sam was so toxic Leaf saw no therapeutic value in continuing. He claims he asked to be removed from the program and returned to prison. “So off I went back to Fergus County jail to await the formality of being terminated. When I received the paperwork, I acted out, said I wasn’t signing any of these lies and threw them on the ground.” It was the Chargers locker room temper tantrum all over again. “I felt like standing up for myself. Waste of time, but I did feel a little bit better.”

On January 23, 2013 he writes to me from prison: “How goes it my friend? Oh, it is just lovely to be away from Nexus and that godforsaken town. Until I’m confident I won’t harm myself and my community and my family with my actions and selfishness, here is where I will stay.”

Leaf feels better when he’s sober and knows it. He’s driven to do the right thing and annoyed when he doesn’t. That’s his spiral: He’s a failure when he does dope, but the dope stops him from thinking he’s a failure. At least for a while. He feels used by pills, but without pills he feels used by society. He feels used by the media. He feels used by isolation from that attention when he’s sober. Celebrity is his relapse trigger. The cure for Ryan Leaf is, unfortunately, not being Ryan Leaf.

January 30, 2013: “Yes, you’re right, the sweatpants was so me. My extremist nature reared its ugly head. I held others accountable at every turn, and it absolutely backfired on me. Yosemite Sam was going to be the one to cure Ryan Leaf. It was a battle again with him until I was escorted off the premises. But if I was a security risk then I’m the goddamned tooth fairy!”

He doesn’t have to continue punishing himself for having fucked up. Failing doesn’t make one a failure. But for Leaf, the painkillers mute a noise only he can hear: other people’s disapproval. He saw this truth at that 12-week epiphany, when he realized, “I couldn’t control anything outside, but I could control my thinking.” Essentially, stop trying to be as bad as Peyton Manning is good. “There were also ego issues,” he once said. No shit, buddy.

But scuffing the shine off his tattered legacy means persuading others to see him the way he fears he must see himself. Mainly, life ain’t a bed of Rose Bowls for everyone who achieves fame and fortune. It’s also hardly news that learning from other people’s mistakes is a splendidly cheap way of improving one’s own life.

February 13, 2013: “I’m where I’m supposed to be,” he writes. “I’m safe, I’m sober, and I’m not harming my family and my community.” He’ll serve out a 60- to 90-day evaluation period before being moved to Montana’s state prison. “I got what I wanted, as you would probably say. All is well, and time moves on.”

This article was originally published in the September 2013 issue of Playboy. Check out more from the issue at playboy.com/magazine.